Approximately 1 in 5 annual US deaths are attributed to cigarette smoking, the largest portion being cardiovascular (CV) -related. However, smoking cessation is difficult due to the addictive nature of nicotine so interventions reducing smoking-induced CV risks while smokers attempt to stop smoking are crucial. Emerging evidence indicates that smoking may exert its CV effects by decreasing arterial compliance (AC). Because data suggest regular exercise improves AC, the general hypotheses of the proposed project are that 1) endurance-trained smokers do not demonstrate a decrease in AC observed in sedentary smokers and 2) these favorable adaptations are mediated partly by a decrease in sympathetic-adrenergic tone. 88 otherwise healthy sedentary and endurance-trained smokers and non-smokers will undergo static and dynamic carotid AC, muscle sympathetic nerve activity, vasoactive hormone plasma concentrations, vascular endothelium-dependent vasodilation, and arterial stiffness measures. The expected results should provide new and clinically useful information concerning the use of regular exercise for the primary prevention/treatment of smoking-induced arterial stiffening as well as insight into its mechanisms.